Assigjtob



Jan. 17, 1933. E. G. BAILEY AUTOMATIC CONTROL SYSTEM Z/g Fi l gd Nov.13, 1924 3 Sheets-Sheet JiZ/EZYZZYF 6M 5 6% 5 WW %W Jan. 17, 1 933. GBAILEY 1,894,616

AUTOMATIC CONTROL SYSTEM Filed Nov. 13, 1924 3 Sheets-Sheet 2 Jan. 17,1933.

5 Sheets-Sheet 3 i i 2 A fizz 9272272" Fatented 65am 3?, E1933 were EVENG. BAILEY, 9F CLEVELAND HEIGHTS, GHIQ, ASSIGNOR, BY MESNE ASSIGN- EMNTS,T BAILEY METER, CGMPANY, A CORPORATION DELAWARE AUTOIMTIC CONTROL SYSTEli Application filed November 18, 1924. Serial No. 749389.

This invention relates to an automatic control system wherein severalfactors require independent or individual control for the attainment ofthe desired result.

5 The invention is shown embodied in an automatic control for boilerplants by which the action of the furnace is automatically regulated tomaintain a substantially constant, or desired, steam pressure under all10 conditions of use, while also maintaining an eflicient action of thefurnace so that the requisite power is supplied with a minimumconsumption of fuel. r

The proper and elficient control of the action of the firing of a steamgenerator depends upon certain well known factors, or natural laws,which will be briefly stated to facilitate the description orunderstanding of the appliances involved in the automatic controlforming the subject of this invention.

The pressure of the steam in a boiler plant may be taken as anindication of the sufiiciency of the heat input to meet the variousdemands for power, for if the heat input is insufficient the pressurewill fall, and, on the other hand, if the pressure rises it shows thatmore heat is being supplied, or more fuel is being consumed, than isrequired to meet the demand. This condition has been availed of forautomatic regulation of boiler furnaces by appliances of various kindsresponsive to the boiler pressure, which act to diminish the draft orthe supply of fuel, or

both, when the pressure rises, or to increase ghe draft or supply offuel when the pressure alls.

In such automatic systems as have been employed pribr to my invention,the fire has been controlled to maintain an approximately constant steampressure, but there is no control of the factors which are involved inefficient combustion of the fuel, and while sufiicient heat may beproduced to meet the varied demands upon the plant, there is noautomatic regulation to prevent excessive combustion of fuel as comparedwith what would be required if the conditions for efficient combustionwere maintained.

Furthermore, in the usual type of regulatthe boiler at the time may be.

ing apparatus the corrective action depends upon the result to beregulated (the steam pressure) being and remaining abnormal. men thedemand for power is above the average or normal, the boiler pressurefalls and brings about an increase of the fire and heat input until itbecomes suficient to supply the increased demand. It cannot, how ever,so long as the demand remains above normal restore the pressure tonormal for in so doing it would again cause the fire or heat input to bereduced, tending to decrease the pressure and calling for further orcontinued correction. Thus, with the usual type of regulator the boilerremains at a pressure below normal so long as the rating or demand forpower is above normal or average, and the pressure remains above normalwhen the demand for power or rating is below the normal.

In the regulating system forming the subject of the present invention,the pressure is restored to normal by the corrective action whatever thedemand for power or rating of There is a definite relation, notnecessarily a constant ratio, between the quantity of steam output andthe quantit of fuel re-. quired for its generation,an in the case of thefuels in common use, such as gas, oil, or coal in various forms, thequantity of air required for perfect or highly eflicient combustion isso nearly proportional to the quantity of fuel that it may be taken as ameasure of the fuel consumed. If an increased demand for steam calls forincreased heat input, or consumption of fuel, there will obviously be acorresponding increase in the supply of air or oxygen required tomaintain the proper combustion of said fuel. There is, therefore, adefinite relation between the flow of air through the furnace,(corresponding to heat input) and the outflow of steam (heat output)when the combustion is eflicient, and a departure from this relationindicates that the conditions, or factors, involved in the combustion ofthe fuel are not correct. If the air; flow exceeds the proper proportionfor any given steam flow, it indicates that an excess of air over what100 is repaired for proper combustion is being supp led to the furnace,which involves a waste or loss of heat, and if, on the other hand, theproportion of air is less, it indicates an excess of fuel, resulting inimperfect combustion and waste of heat is unconsumed smoke or s.

In Reissue Patent No. 15,080, dated April 12, 1891, I have described amethod of indicatin the relation of steam flow to air flow, and inPatent No. 1,257,965, I have shown an indicator of the kind now wellknown as the Bailey air-flow steam-flow meter, which indicates when theroper relation of steam How and air flow exists at any rate of output ofsteam, and also indicates any departure from such relation, suchindications having been used to inform the fireman of the condition ofthe furnace in order that if eflicient conditions were not prevailing aproper correction could be made either by increasing the fuel suppl orthe air supply, or, in the case of sohd fuel, by correcting thecondition of the fuel bed. In the present invention the automaticcontrol system causes the proper corrections to be made automatically,or itself performs what the fireman was called upon to perform when onlythe indicator or meter was used. The present invention is applicable toa lant containing a number of individual ilers and furnaces affording acommon supply of steam and the a paratus serves to maintain the pressurethe steam output substantially constant at all ratings, and also tomaintain the combustion in each of the individual boiler furnaces at astate of high efliciency.

The appliances involved in the control system forming the subject ofthis inventlon include a primary controlling device responsive tovariations in steam pressure and acting to increase or decrease thecombustion in all of the furnaces simultaneously, and a ;secondarycontrolling appliance, or readjustment control, including and responsiveto a Bailey air-flow steam-flow meter, or some equivalent appliance,cooperating with the main control to govern the supply of air .and fueltoeach individual boiler, so as to pulverized coal, the rate of fuelsupply may,

be varied by the action of a coal feeding applance, the air supply beingautomatically regulated under control of the Bailey airflow steam-flowmeter, concurrently with the primary control of fuel and air in responseto a pressure gauge, or element responsive to variations in steampressure.

There are various other features involved in the proper action of theautomatic controlling apparatus forming the subject of this inventionwhich will be best understood when explained in connection with theconcrete embodiment of the invention illustrated in the drawings forminga part of this specification, in which Fig. 1 is a diagrammatic viewrepresenting the general relation of the various components of thecontrol system to one another and to the steam plant to be regulated, asufficient portion of one boiler and furnace bein shown to indicate therelation of the ot er appliances thereto.

2 is a diagrammatic view showing the cooperative relations to oneanother of the several instrumentalities, and the provision fortransmitting the action from one to another of the severalinstrumentalities.

Figs. 3, 4, and 5 are diagrammatic views indicating difierent conditionsof the circuit connections, which will be hereinafter explained.

Fi 6 and 7 rear and end elevations, respectively, of the secondarycontroller showing a suflicient portion of a steam-flow airflow meterfor an understanding of its relation to the other components of thesecondarv controlling instrument, and

igs. 8 and 9 are side and end elevations of a portion of the primarycontrolling instrument, a portion of Fig. 9 being shown in section toillustrate a feature of construction which will be explained.

General organization The general organization of the components in theirworking relation to one another is shown in Fig. 1 as applied to aboiler furnace, 200, which may be one of a battery or number of boilersgenerating steam for a common sup ly, the intensity of the fire or inputof heat ing as shown in this instance governed primarily in part by adamper, 201, in the uptake, 202, the shaft, 203, of which damper isadapted to be operated by a worm and sector, 204, actuated by a shaft,205, itself actuated by the control or corrector driving mechanism shownat 100, which also operates a rheostat, 206, governing the operation ofa motor, 207 for a powdered coal feeding appliance, 208, from which thepowdered coal or fuel is delivered through a duct, 209, to the furnace.The input of heat from the furnace may thus be increased by increasingthe speed of the fuel feed motor, 207, and thus supplying the fuel at amore rapid rate, and also increasing the draft or supply of air bygiving a wider opening to the damper in g the uptake, 202. Converselythe input of heat is diminished by reducing the speed of ture fromnormal and consequently the character and amount of correction required,and appliances which govern in part the action of the corrector drivingmechanism, 100, in such manner as to increase the feed of fuel and flowof air in response to a reduction of steam pressure from normal, or todiminish the feed of fuel and flow of air in responseto an increase inboiler pressure.

The secondary or read ustment control is I afforded by the applianceshown at 40 in Fig.

1, one of which pertains to each individual boiler and furnace and isherein shown as comprising a Bailey steam-flow air-flow meter, ofsubstantially the character of that shown in Patent No. 1,257,965, datedMarch 5, 1918, to which reference may be had for an understanding ofsaid instrument, it being sufiicient for the purposes of the presentcase to state that the instrument shown at 40 in Fig. 1 also comprisesmechanism of a character similar in some respects to that contained inthe primary control instrument, 2, which also governs in part the actionof the corrector driving mechanism, 100, and modifies the action thereofwhich would result from direct control by the primary controlinstrument, 2, if acting alone.

The above mentioned components are so organized that a fall of boilerpressure, indicating deficiency of input of heat, causes the primarycontrolling device to affect the corrector driver in such manner as toincrease the fire, by acting through the rheostat, 206, to increase thespeed of the fuel feed motor, 207, and at the same time by actingthrough the shaft, 203, on the damper, 201, to increase the air supply,and conversely a rise in boiler pressure causes lessfuel and less air tobe supplied.

The secondary controller is at all times responsive to the steam-flowair-flow meter and acts to adjust the air flow through the action of theshaft, 203, upon the damper, it

being possible for this action to take place,

when required, concurrently with the action.

mal pressure and with the fuel supply sulficient to maintain the higherrating.

When, on the other hand, the pressure rises above normal, indicating alower rating or demand for power, the primary control acts through thecorrector driver, 100, in a similar manner to reduce the supply of fueland air until the heat input is only suficient to maintain the boiler atthe lower rating but with the pressure brought back to normal andmaintained there until further change of rating is called for, thesecondary controller insuring that the supply of air is corrected tomaintain efiicient combustion.

Before describing the various instrumentalities by which the desiredresults are attained, it may be stated that the action is such that theedect of the primary controller is to increase the supply of air inadvance of, or

more rapidly than, the supply of fuel is increased when increasing theheat input of the furnace to meet a'larger demand for power, and, on theother hand, in the operation of reducing the output of power the supplyof fuel is reduced in advance of, or more rapidly than, the supply ofair, so that an abnormal excess of air is present when any change,either increase or decrease, is being made in the rate of supply offuel.

It may be noted that, especially in the case of gaseous or liquid fuelor of pulverized solid fuel, any one of which is consumed practicallyconcurrently with its entrance to the combustion chamber, it isdesirable to maintain at all times a slight excess of air over thatwhich theoretically just combines chemically with the fuel, and it isespecially desirable to insure that such excess should exist whilechanges in the rate of supply of fuel are being made, as any excess offuel over what will combine with the oxygen supply is wasteful, smokeproducing, and otherwise objectionable, and may even be dangerous orcause an explosion to take place.

While the controlling apparatus is so constructed as to cause anincrease in the excess of air while changes are being made, theacprimary controlling appliance, 2, the flow of air will be furtheradjusted bythe secondary, or readjustment, appliance, 40, to the properrelation to the then rate of fuel supply for eflicient combustion.

The construction of the controlling devices furthermore, is of suchcharacter thatithe rate of corrective action, or readjustment increasesthe greater the amount of readjustment required. That is, of the steampressure should be rather suddenly reduced by the amount of two or threeper cent, the increase of delivery of fuel and air to the furnace wouldbe much larger or more rapid than would be the case if the pressure hadfallen off only one per cent or a fraction thereof.

The construction of the primary controlling device, furthermore, is suchthat the corrective action depends upon whether the change of steampressure is towards or away from normal, the construction being suchthat account is taken of the lag or necessary lapse of time between themoment when a correction, such as an increase of fuel, is made, and thetime when the boiler pressure responds thereto, which will be some timelater as the water cannot instantly absorb and respond tothe increase ofheat. The controller t us anticipates the result that will follow itsaction, and awaits the appearance of the result before taking furtheraction.

P16111017; control instrument The primary control instrument, shown inits entirety at 2 in Fig. 1 and somewhat diagrammatically at 2 in Fig.2, a portion of the mechanism being shown more in detail in Figs. 8 and9, comprises an indicator or appliance responsive to variations in steamressure in the boiler, the heat input to which,

is to be controlled, which appliance may be likened to an ordinary steamgauge and is shown in Fig. 2 as comprising a Bourdon tube, 3, connectedby a pi e, 4, with the battery of boilers to be contro led, and asoperating, in use to the changes of pressure, an arm or pointer, 5,which will be referred to as the indicator, which carries at itsextremity a bearing piece, 6, best shown in Fig. 8, the position ofwhich indicates the pressure in the boiler.

Cooperating with the indicator is a feeler, 7, also best shown in Fig.8, which has a continuous slow to and fro periodic movement relative tothe contact piece, 6, of the indicator. 1

Said feeler is carried by a sliding frame, 8, (see Fig. 8) having a camroller, 9, acted upon by a cam, 10, which is continuously rotated at aslow speed by gearing, 12, driven by a worm and worm gear, 13, from theshaft, 14, of a continuously running motor indicated diagrammatically at15 in Fig. 2.

The feeler, 7, thus periodically moves towards the indicator bearingpiece, 6, but when the indicated pressure is normal and said indicatoris in its intermediate or normal position said indicator is in the path.of a deep notch or recess, 16, in the feeler, which consequently doesnot have any eflective engagement with the indicator and does not haveany efiective action upon the correcting instrumentalities, as obviouslyno correction is needed so long as the pressure remains at normal.

If, however, there is a rise or fall in boiler pressure the indicator,5, in responding thereto will move the bearing piece, 6, away from thenotch, 16, in the feeler to one side or to the other, it being shown inFig. 8 as having been moved in response to a decrease in boiler pressureindicating a call for increased fuel.

In this movement of the indicator the bearing piece, 6, is broughtbetween a transmitter actuator and a portion, 18, of the feeler, 7, atone side of the deep notch, so that in the next movement of the feelertowards the indicator bearing piece, 6, the feeler will move the saidbearing piece with it and through the said bearin piece will move anactuating frame or slide, 20, which 0 erates the controller roper or thetransmitter of the control action to the correcting device which is tobe operated, in this case to increase the input of heat.

As shown in this instance, the transmitter is a circuit closer, 22,having the anvil contact carried by the main or body member, 23, of thecircuit closer, while the other or relatively movable contact is carriedby a finger, 24, pivotally connected with the said body member at 25 andacted upon by a s ring, 26, tending to separate the contacts an keep thecircuit open.

The said transmitter, in this case simultaneousl controls two responsiveinstruments, electro magnets or solenoids 1n the control drivinginstrument, 100,) which act one upon the fuel supply, and the other uponthe air supply, and concurrently efiect a gradual increase of the fueland air supplies as long as the circuit remains closed at 22, as will behereinafter described.

The action of the driver, 100, on the correcting devices is slow andgradual so that the amount of corrective action depends upon thetimeduring which the driver is actuatin the correcting devices, which inturn depends upon the length of time that the circuit remains closed at22, by the transmitter of the primary controller.

Referring again to the feeler, 7, it will be seen at the parts 18, 19,that the sides of the inactive notch, 16, are cam shaped or of varyingheight, being shown in this instance as formed in a series of steps oneor another of which engages the indicator bearing piece, 6, according asthe indicator is moved a greater or less distance from normal position.

As shown in Fig. 8, the bearing piece, 6, is in position tobe engaged bythe second step from the notch and thus produces a greater movement ofthe actuator, .20, than would be the case if it were moved only to thefirst step step or anything beyond,

Thus the amount of movement imparted to the actuator, 20, and the lengthof time of closure or the circuit at 22, varies according vto amount ofchange in boiler pressure from normal, affecting the indicator, 5, whichaccrues in the period'between successive movements of the ieeler.

This variation in amount of movement of the actuator, 20, produced bythe ieeler ertects the variation in the time duration or": the contactof the circuit closer, 22, and consequently the amount of correctiveaction in the following manner.

a The body member, 23, of the circuit closer is fixed to a tubularshaft, 28, which is tric-v tionally driven at a slow speed relative tothe speed of the feeler driving cam, 10, by gearing, 29, from the shaft,14:, of the motor, 15, which actuates the feeler, the action being totend to turn the circuit closer bodily (both members together whether incontact with one another or not) in the direction to carry the movablemember, 24, towards the actuator, 20, this bodily movement of thecircuit closer being limited by a stop, 30, (see Fig. 8) in suchposition that it normally remains standing with the contacts separatedby the action of the spring, 26, when the actuator, 20, is in normalposition, as is the case when the ieeler, 7, receives the bearing piece,6, in its notch, 16, or when the said feeler is at or near the end ofits movement away from.

the said contact piece.

When the indicator is away from normal position as shown in Fig. 8, andthe leeler, 7, makes its movement towards the bearing piece, 6, of thesaid indicator, the latter will be engaged by a step of the raisedportion- 18, of the feeler and will in turn engage and move the actuatorslide, 20, which will first move the movable circuit closer member, 24:,towards the body member until the contacts come together at 22, closingthe circuit, after which the further movement of the actuator, 20, willovercome the frictional engagement between the circuit closer and itsdriving mechanism and will then produce a, bodily pivotal movement ofthe entire circuit closer around the axis of the shaft, 28, in thereverse direction to that'in which the circuit closer is carried by thefrictional drive of said shaft, 28, the circuit remaining closed duringthe period in which'the actuator, 20, is thus turning the said circuitcloser about its axis The moment-when the actuator, 20, begins itsreturn movement, in the return stroke of the leeler, 7, the movablemember, 24, of the circuit closer separates from the main member andopens the circuit, the period of closure of which thus depends upon thelength of movement of the actuator, 20, by the feeler, 7, which in turndepends upon the step or portion of the cam or modifier, 18, of thefeeler which has engaged the indicator hearing piece, 6, depending uponthe amount of departure from normal of the pressure indicated in thetime occupied by the to and fro movement of the feeler. Thus a slow dropin pressure, moving the indicator from. normal only to the first step ofthe feeler in the time occupied by one backward and forward movement ofsaid feeler, would produce only a very short period of closure of theCii cuit, and consequently a very short period of corrective action,which might be sulficient to correct for the slight change in outputindicated by the slow change in pressure; but a larger change inpressure, in the same interval of time, indicating the need for agreater correction, would produce a longer movement of the actuator, 20,and consequently a longer period of closure and a correspondinglygreater corrective action resulting therefrom.

Inasmuch as there is some time lag between the correction, or change offuel feed and draft, and the change or" pressure responsive does not atonce return to normal position, as y it may be found that the correctionalready made withoutfurther addition will restore the pressure to normalas soon as the correction has had time to take effect in the genera=tion ofsteam.

Consequently the control instrument is so devised that upon the nextaction or the feel er, upon the actuator, 20, there will not be afurther correction corresponding to that made at the first correctiveaction of the ieeler, this being due to the slow return movement of thecircuit closer towards its normal position in engagement with the stop,30.

Consequently if there has been no further departure of pressure fromnormal at the next operation of the feeler, the contacts of the circuitcloser will be brought together i to restore the pressure to normal itthe initial corrective action was insuficient to do so.

If, however, the pressure should dro further before the next operationof the color, 7, the bearing piece, 6, would be engaged by a higher stepand the actuator, 20, would be moved to a greater distance thus a ainclosing the circuit at 22 and moving e circuit its ia-o closer bodilystill further from the normal position, the time of contact beingsubstantially the same for the second. step as for the first, becausethe circuit closer is not operated in the second step until after theactuator has made a movement about equal to that derived from the firststep.

Thus a continued but relaively slow variation of pressure from normal inthe'same direction will produce a further but relatively smallcorrection in the same direction, and such corrections would continue tobe made so long as the variation continued slowly in the same direction,but when the result of the correction begins to appear and the indicatorbegins to return towards normal, its movement presents the bearingpiece, 6, to successively lower steps of the modifier, 18, of thefeeler, and consequently no further corrective action takes place duringthe return movement of the indicator towards normal, although the actualdeparture of pressure from normal in the-same direction might continuefor some little time.

If the change in pressure had been sudden and relatively lar e as in thecase of a sudden large increase in emand for power, the indicator in theinterval between movements of the feeler would move to a positionrelative to the feeler which would cause the actuator, 20, to produce arelatively long continued movement of the circuit closer and closure ofthe circuit.

At, or near, the extreme or maximum movement imparted by the feeler, dueto an indication of a ,very large change in pressure, the circuit closerwill be carried against a 'eldin stop 32, which will yield to permit 0the re ativel extensive movement of the circuit closer, ut in the returnmovement of the actuator, 20, will overcome the frictional connectionbetween the circuit closer and its drivin mechanism and thus carry thecircuit closer ack towards normal position sufliciently to cause anothersubstantial closure of the circuit to take place at the next succeedingmovements of the actuator, 20, unless, or until, the indicator begins torespond to the correction and begins to move back towards normalposition.

The primary controlling instrument includes another circuit closer, 220,(see Fig. 9) in all respects similar to the circuit close 22, which hasbeen described, except that its actuator, 2000, is operated by theindicator bearing piece, 6, and the modifier or step surface, 19, of thefeeler when the departure of the pressure from normal is in the otherdirection to that which operates the circuit closer, 22.

duced by the parts responsive to the circuit closer, 22.

The actuator, 20, engages the movable member, 24, of the circuit closerby a bearing piece, 35, adjustably fixed at a desired point in a slot insaid circuit closer member, so that by setting it at a greater or lessdistance from the axis of movement of the circuit closer acorrespondingly less or greater angular movement of the circuit closerwill result from the same movement of the actuator.

The actuators and feeler have their return movement produced by springs,36, which hold the cam roller, 9, against the actuating cam, 10.

The patterned or stepped acting portions, 18, 19, of the feelerconstitute a modifier of the corrective action, by which the amount ofcorrection is made to depend upon the rate of variation of the steampressure or variable factor for which the correction is made. If thevariation is at a slow rate the corrective action will be small, but ifmuch greater variation takes place in the same period of time the.correction is correspondlarger.

e retarder or provision for efiecting the relatively slow returnmovement of the circuit closer to normal position after each operationconstitutes an anticipator, as it delays further operation of thecorrector in anticipation of and while awaiting the result due to thecorrection which has been made.

By these expedients, the modifier in the initial corrective action, andthe retarder for subsequent actions, over-correction is usuallyprevented, and when a chan e of rating, or increase or decrease of demanfor power relative to normal or average, takes place there is acorrection of the fuel sup ly suflicient to make u for the change 0?rating, and to restore t e pressure to normal, after which all partsremainin normal position until some further change in the factor to becontrolled takes place, when the corresponding correction is made.

Corrector dn'ver The roper corrections are made in the fuel an airsupply to rovide for increased or decreased input of iieat by anactuating machine indicated as a whole at in Fig. 1, one such machinepertaining to each individual boiler furnace. The essential componentsof the machine are shown in perspective in Fig. 2, the general characterof the mechanism being such that it causes a corrective action ormovement of the thing or things to be corrected (in this case fuel feedand air supply) to be made in one or the other direction at acomparatively slow rate and during periods of time that are undercontrol of the rimary controlling instrument, 2, above escribed, and ofthe secondlid ary controlling instrument, A0, as will be explainedhereinafter.

Referring to Fig. 2 the corrector driver Comprises a connected train ofmechanism normally kept in continuous operation by a motor, 110, whichprimarily drives a shaft, 112, which is one of six shafts numbered from111 to 116 respectively (which, with associated parts will behereinafter referred to as first, second, and so on, for convenience andbrevity) all of which are driven by the train or" gearing, 117, in suchmanner that.

the shafts of each of the several pairs, 111, 112, and 113, 11 1, and115, 116, are rotated in opposite directions and at an efiectiverelative speed that will be explained here inafter.

The said shafts all have loose upon. them clutch members, 118, eachprovided with gears and the gears oi the pair of clutches on the firstand second shafts mesh with a gear, 119, on shaft 120, connected by wormgearing with one member, 121, of a diilerential gearing, the othermember, 122, which is similarly connected with a shaft having a gear,123, meshing with the clutch gears of the intermediate pair '5 shafts,113, 114,

The difierential gearing be of the usual well known character, themembers, 121 and122, being loose upon the shaft, 131, and comprisinbevel gears meshing with opposite sides or the intermediate, 130, whichrotates on an axis fined to the shaft, 1131', Consequently, if one or?the members, 121' or 122, is stationary while the otherrotates theintermediate will roll around the periphery of the stationary one andwill cause the shaft, 131, to rotate at one-half tie speed of themovable member. 1i" both members turn equal speeds but in oppositedirection the intermediate, 180, will merely rotate upon its axiswithout turning the shaft, 181, while if both members turn at the samespeed in the same direction the intermediate will act merely as a keyconnecting them to the shaft, 131, which will then rotate in the samedirection and at the same speed as the two members of the diderential.For all intermediate speed and direction relations between the twomembers, 121, '122, the shaft, 131, will be rotated accordingly, at theaverage, or

one-half the algebraic sum of the rotations of the two mernhers,x

The third pair of clutches are similarly.

geared to a'gear, 125, on the shaft, 126, connected by worm and wormgear, 127, and suitable further connections with the controlling shaftof the rheostat, 206, which varies the speed or" the fuel feed motor,207, and is thus the corrector for the fuel supply to meet the demandsput upon the furnace and boiler,

The shaft, 131, carrying the intermediate member, 130, between thedifierential gears, 120, 122, is connected through any suitable gearing,such as that conventionally shown, at 132, 204, with the damper, 201, orcontrol of the air supply and is thus the corrector for the fiow of airto be used with the supply 33 fuel which is corrected by the rheostat,

By this construction it will be seen that if one of the clutches of thefirst pair is engaged and consequently connected with the correspendingshaft it will cause the corresponding gear, 119, to be turned in onedirection (the other clutch member then idling on its shalt) while ifthe clutch of the other shaft of said first pair is engaged, the saidgear, 119, will be turned in the opposite direction, the same being trueof the second and third pairs clutches and the gears, 123and 125, drivenby them respectively.

1n the construction of the machine an in terloclring stop is provided,as shown (for the pair only) at 140, between the clutches'o'l each pairwhich operates to pre vent the second clutch of apair from being throwninto engagement while either one is in engagement and thus preventspossibility of clashing of the gears and the damage or breakage thatwould be likely to ensue thererrom,

Referring to the third pair of actuating shafts, 115, 116, and clutchesthereon, it will be seen that with the clutch of shaft 115 engaged, therheostat,'206, will be operated in one direction, say to increase thesupply of fuel, while if the other clutch, on shaft 116,

isengaged, the rheo'stat will be operated in the opposite direction tomake the reverse correction or provide "less fuel per unit of time,

The several clutches are shown as operated by instruments, 1&1, 1 12,143, 14 1, 145,- 1 16,

which. are responsive to the transmitters Irom the primary'andsecondary'controlinstruments, being shown as solenoids under control ofthe circuit closers, 22, and 220, of the primary controlling instrument,2, above described, and of a somewhat similar transmitter forming a partof the secondary control instrument, or, when desired, under manualcontrol by an attendant as will be I hereinafter described.

lit it be assumed that the member, 122, of the diiierential is keptstationary, rotation of the member, 121, under the actuation of theshalt, 120, will cause a movement of the shaft, 131, and correspondingmovement of the damper or correction of the air flow and it will be seenthat the movement will be in one or the other direction, to increase ordecrease the air flow, according as the clutch on one or the other ofthe first and second shafts, 111, 112, is engaged.

in the present example the operation of the air control under actuationfrom the first shaft, 111, increases the air supply, and from the secondshaft 112, diminishes the air suply, and similarly the actuation of theshaft, 126, by the fifth shaft, 115, increases the rate of fuel supplywhile actuation from the sixth shaft, 116, diminishes the rate of fuelsupply.

The solenoids, 141, 145, corresponding to the shafts, 111 and 115, areconnected to the circuit closer, 22, of the primary controllinginstrument so that at the time when said circuit closer is closed theclutches on said shafts will be in engagement'and correction will bemade in the way of increasing both the fuel and air su ply concurrently.

Similarly the so enolds, 142 and 146, as-..

sociated with shafts, 112 and 118, are connected with the circuitcloser, 220 of the primary instrument (which responds when boilerpressure rises above normal) and when said circuit closer is closed saidshafts will operate to reduce the supply of fuel and air concurrently.

Furthermore, the relative speed of rotation of the several shafts issuch that in the operation of increasing the supply of fuel an air bythe action of the first and fifth shafts, 111, 115, the increase of airis made at a relatively higher rate'than the increase of fuel, andconversely the relative speed of the second and sixth shafts, 112 and116, is such in reducing the supply of air and fuel that the supply offuel is reduced at a relatively greater rate than the supply of air, sothat in making any change, either to increase or to diminish the fire,the excess of air above that required for perfect combustion isincreased, while the change is being made, so far as the effect of theinstrumentalities under control of the primary controlling instrumentare concerned.

The aring connections between the shafts 112 an 116 and from said shaftsrespectively to the air control corrector or damper, 201, and the fuelcontrol corrector or rheostat, 206, are such that when the clutches onsaid second and sixth shafts, 112 and 116, are engaged the operation ofthe rheostat, 206, would be relatively faster than the operation of thedamper, 201, so that the fuel supply will be reduced at a relativelygreater rate than the air supply.

The shaft, 111, which when its clutch is engaged causes an increase ofthe air supply, is driven from the gearing, 117, at a higher rate ofspeed than the others (by a somewhat smaller driving gear than theothers in the train) and consequently when the first and fifth shaftsare operating to increase the air and fuel respectively, the aircorrecting device will be moved at 'a relatively greater rate to producearelatively greater increase of air than of fuel.

The intermediate pair of shafts, 113 and 114, are under control of thesecondary controlling instrument, which will be described d ment, 2, asabove stated, always ten later, although it may be noted at this pointthat it contains two circuit closers, similar in character to those ofthe primary controller, one of which" governs the solenoid, 143, whichoperates the clutch associated with the third shaft, 113, while theother solenoid, 144,0perates the clutch associated with the fourthshaft, 114. Thus when one of the clutches of the second pair is inoperation the member, 122, of the differential will be operated in thedirection to increase the air flow, while the other clutch of said pairwhen engaged with its shaft will similarly cause a diminution in the airflow, and through the differential connection the movement, or themodification of the movement, of the damper, due to the action of eithershaft 113 or 114, may take place concurrently with the action of eithershaft 111 or 112, under control of the primary controlling instrument,or may take place at any time while the clutches of shafts 111 and 112are not in operation.

Thus, while the primary controllin instruds to increase the excess ofair flow while any change is being made, the secondary controllinginstrument acting through the differential is always under control ofthe steamfiow air-flow meter forming part of the secondary instrumentpertainng to each boiler, and operates to correct the air flow for itsown boiler furnace, and it may operate concurrently with the operationdue to the primary control or after that operation is completed. It, infact, stands ready at all times to correct the flow of air according torequirements for efficient combustion, as indicated by the secondarycontrolling instrument, whether an increase or a decrease of air isrequired.

Secondary control z'mtrwment The secondary control instrument designatedas a unit, 40, in Fig. 1 is best shown as to its working components inFigs. 6 and 7.

Like the primary instrument, it comprises an indicator the change ofposition of which indicates the character and extent of correction ruired, in this case increase or decrease 0 air supply to the furnace.

It also comprises a feeler similar in character to that of the primaryinstrument already described, and actuators and circuit closers operatedthereby in a similar manner, except that there is no retarder orappliances for providing for time lag in the response to correction, asnone is needed in the case of the adjustment of the air supply when fuelof the nature of pulverized coal is used.

Referring to Fig. 6, which shows the working components of a Baileyair-flow steamflow meter of the kind forming the subject of Patent No.1,257,965, the component responam: to the air flow through the furnaceoperates upon a lever, 41, pivoted at 42 and acting through suitablelinkage upon a po1nter, 43, said lever, 41, being rocked in onedirection by increase and in the opposite dlrection by decrease in theair flow through the furnace.

The part responsive to steam flow acts upon a lever, 44, pivoted at 45and actlng through suitable linkage upon a pointer or indicator, 46.

The levers, 41 and 44, which respond to air flow and steam flowrespectively are connected by links, 47, 48, with a floating bar orlink, 49, having a bearing piece, 50 (see F 1g. 7) 1nterposed betweenthe feeler, 51, and carriers or actuators for the movable members of twocircuit closers, 60, 61, the normally stationary or anvil members ofWhich are yieldingly supported, as indicated in the case of the upperone at 62 in Fig. 7.

The feeler, 51, is operated with a continuous slow back and forthmovement by a cam,

52, operated through suitable gearing indicated at 53, by thecontinuously running motor, 55.

The Bailey steam-flow air-flow meter,

which itself forms no part of the present 1nvention, is devised toindicate the relation between steam flow and air flow at which efii-.cient combustion is maintained, the steamfiow air-flow. pointers orindicators, 43, 46, being in substantially coincidence when the properrelation exists and being both movable in response to changes in steamflow and air flow.

So long as the movement of the pointers is practically coincident, as isthe case when the proper relation is maintained, (although both factorsmay be individually undergolng change) the floating link, 49, Wlll bemerely turned about its central point where the bearing piece, 50, islocated and will not change the position of said bearing piecevertically, but if one of the pointers moves when the other does not, ormoves at a diflerent rate from the other, thus indicating a departurefrom the proper relation between the steam flow and air flow, one end ofthe link, 49, will rise or fall to a greater extent than the other andconsequently the bearing piece, 50, at or near the middle of the linkwill be raised or lowered as the case may be.

If, for example, the air flow is less than it should be for the existingrate of steam flow the bearing piece will be moved upward, and on theother hand if the air flow is greater than required for the combustionto maintain the existing steam flow, the bearing piece will be moveddownward.

The feeler, 51, has a central notch, and

stepped or cam shaped engaging portions at the side of said notch, beingsimilar to-the feeler of the primary controller in this respect andconsequently needing no. further description, and it will be seen byreferring to Fig. 7 that when the indicator bearing piece, 50, is innormal position, as when the relation between steam flow and air flow iscorrect, said bearing piece will be received in the notch of the feelerwhen moved towards it by the cam, 52, and no effect will be produced.

If, however, the air flow is greater than it should be for normalcombustion, as is the case when a change is being made in response tothe primary control instrument, as before explained, the bearing piece,50, will be moved downward and will come between the modifier or steppedportion of the feeder and the actuator or bearing piece of the lowercircuit closer, 61, moving the said bearing piece and circuit closermember towards the anvil member of the circuit closer and thus closingthe circuit during a portion of the movement of the feeler, andenergizing the solenoid, 144, of the fourth shaft of the correctordriver which responds with the tendency to supply less air.

The anvil is shown as yielding and spring pressed towards the movablemember of the circuit closer and consequently will maintain the contactduring the further movement of the movable member after the contact hasbeen made and in the return movement until the anvil member arrives atnormal position and the contacts are again separated.

Thus the time duration of the circuit closure is varied in accordancewith the distance the bearing piece, 50, of the indicator is moved fromnormal position, giving a longer period of corrective action the greaterthe deviation of the air flow from the proper relation to the steamflow.

Tn caseof deficiency of air the bearing piece, 50, of the indicatorwould be moved upward and the actuator for the other circuit closer, 60,would be operated in a similar manner to make a correction in the way ofincreasing the air flow to the furnace.

Referring now to the relation of the secondary control instrument to thecorrector driver, the circuit closers, 60, 61, control the responsiveinstruments or solenoids, 143 and 144, pertaining to the clutches on theintermediate pair of shafts, 113, 114. Thus, according as one or theother circuit closer is operated, one or the other of the clutches willbe connected to the intermediate gear, 123, and will drive the-member,122, of the differential in the proper direction to operate the shaft,131, and connections to the damper or air controlling device in suchmanner as to increase or decrease the air flow as is called for, thisoperation taking place through the differential connection regardless ofthe action of the other member, 121, of the diflr'erential due to theprimary control instrument. 1-

Transmitting connections In the embodiment of the invention herein shownthe transmitting connections between the several instruments are thoughthe invention is not ii; construction, as obviously other mechanism,such for example pneumatic or even mechanical connect, us or linkage,might be employed.

The electrical connections present example oi the in shown in Fig. 2 andreou' planation or analysis, as understood by those 2am As there shown,a main s 500-, has a branch, 501, motor, 110, of the corre and a branch,502, supp of the primary instrument, a i 503, supplying the motor, ofthe secondary instrument.

The primary and seco rv inst uments have provision for chan g omautomatic to hand operation whe equired under control of switchesindicated as a whole in Fig. 1 at 02 for the primary instrument, 2, and04 for the secondary instrument, L0.

The primary instrum nt in the normal automatic operation of 1eEZPTJQTZLUS controls only the fuel air actors, producing through theacticr first and fifth shafts o the corrcc crease in supply of fuel a dconcurrently, or through the action o second sixth shafts causing lessfuel and less air to be supplied.

The switch ()2 merely changes the connection from the automatic c cuitclosers, 2:2 and 220, to two correspond a push buttons, M, L, (seeFig. 1) so th when the said switch is in the No. positio the push buttons control the circuit, 16. the operator by pressing the button I willcause the correct-or driver to give more u i and more will cause air, orby pressing the bi ton less fuel and less air to be led to the "furnace.The switch 04 of the secondary controlling instrument has four workingpositions, the one numbered 1 being normal, or for corn plete automaticoperation making the connections as indicat nmatically in Fig. 2, whileif the switch is placed at the No. 3 position it makes the connectionsindicated diagrammatically in "i 5, with the push buttons M, L, such adetailed e2:- v.ill be readily the art.

pply line, 500 supplying the nachine, e motor, 15, a branch, the'l'eeler operation of push button M gives more fuel more airconcurrently, while operation of the push button L gives less fuel andless air concurrently, these hand operations thus being brought withincontrol of an attendant at instruments, which may be located at a placein the plant more or less remote from the instrument and from oneanothere er an mk Other changes in the connections produced by theswitch 04 the secondary instrument are indicated diagrammatically inFigs. 3 and 1, that shown in Fig. 3 being the position in which the airsupply only may be operated by the push buttons, while that shown inFig. i is such that the "fuel only is controlled by the push buttons,increasing or diminishing the fuel ced according as the button M or L isoperated.

With the connections as shown in Fig. 2 the push buttons of bothinstruments are out of circuit and the operation is automaiicthroughout.

Referring to the diagram, wire 510 connects with one terminal of each ofthe sole noids, 141, 1-42, 1 .25 and 1 1 pertaining to the first andsecond and the nith and sixth shafts of the Corrector driver.

When the switches 0:2 and O i are in normal position for completeautomatic operation the connection from wire 510 of the switch 0% in thesecondary instrument is continued on to the positive side of themainsupply circuit, 500, so that connection in some way from thenegative side of the main circuit to the other terminal or any one ofthe solenoids of the Corrector driver will complete the circuit throughsaid solenoid and energize the same.

The wire, 510a, similarl' terminal of each of the mi noids, 143 and 1 11, per' i a and fourth shafts, which are un er control of the secondarycontrolling instrument.

Wires 511, 512, etc, extend from the other terminal of each of theseveral solenoids to the correspondingly marked connections at theswitch O 0'5 the secondary controlling instrument, 3, 5) and in thenormal position of said switch the said connections 511 and 515 arecontinued to one member of the circuit closer, 22, of the primaryinstrument so that when said circuit closer is operated the first andfifth clutches are operated, and the fuel supply and air iiow arecorrected by an increase of each.

Similarly the wires 512 and 516 connect to one member of the othercircuit closer, 220, of the primary instrument, so that when closed bythe action of the i eeler and actuator, as hereinbefore described, theclutches of the second and sixth shafts of the controller driver will beoperated to give less fuel and air.

The other member of: each of the circuit closers. 22, 220, is connectedby a branch, 505. (see Fig. 2) with the negative lead, 500, of the mainsupply circuit, thus completing the circuits of the correspondingsolenoids, 141, 145, and 142, 146, when said circuit closers areoperated.

Similarly the wires 513, 51 1, connect to one member of each of therespective circuit closers, 60, 61, of the secondary instrument, the

-ino to the third M and other members of which are connected by branch506 to the negative lead, 500, so that the circuit of the third orfourth solenoid is closed by the circuit closer, 60, or 61, according asmore or less air is required.

As shown in Fig. 2, the main supply circuit, 500,.and the controlcircuits from the primary controlling instrument, extend beyond thesecondary instrument, this being to indicate that they may lead to othersecondary instruments pertaining to other boilers, all of which form asingle steam generating unit or battery under control of the singleprimary instrument, 2.

Referring to Fig. 2, the switch 02 of the primary instrument is shown asa three-pole or three-arm switch and it will be seen that if thrown tothe other position it will merely transfer the connections from theautomatic circuit closers, 22, 220, to the push buttons, M, L, whichwill then operate the first and fifth or the second and sixth clutchesconcurrently, according as the-push button M or L is operated.

So far as the control by the primary instrument is concerned, thecircuit connection might lead directly from the circuit closers or pushbuttons thereof to the terminals, 511, 512, 515 and 516, of thesolenoids of the corrector driver. They are, however, passed by branchesthrough the switches 0-1 of the secondary instruments, so that thecorrection or change of fuel and air supply either concurrently orindividually, may be made by an attendant at any of the secondaryinstruments.

hen the switch, 04, is in the position numbered 1, in Fig. 1, theconnections are as indicated in Fig. 3 in which it will be seen that thewires leading from the first and second and the fifth and sixthsolenoids are not connected with anything beyond the switch, so thatcontrol is taken entirely away from the primary instrument. Furthermore.the connections, 513 and 514, from the third and fourth solenoids areshifted from the connection with the automatic circuit closers, 60, 61,of the secondary instrument to the push buttons, M and L, thereof, whilethe connection 5100 from the positive terminals of the said third andfourth solenoids is connected by branch 510?) (see Fig. 2) to the thisposition of the switch of the secondary instrument the attendant at thatinstrument sixth are disconnected and the latter (wires.

515, 516 are connected to the push buttons of the secondary instrument,while the positive connection, 510, from said solenoids is connected tothe branch 510?) leading to the positive main lead, 500.

In this position, therefore, the operator at the secondary instrumentwhere the switch 04 is set in the No. 2 position, can increase ordiminish the fuel supply by pressing the but- ;on M or L, and no othercontrol is provided Thus it will be seen that with the switch 04 eitherin the No. 1 position as shown in Fig. 3, or the No. 2 position as shownin Fig. 4-, or alternately in either of these positions, the boilerwhose ratio of fuel and air may be automatically controlled by thisparticular controller 40 will be entirely cut off from automatic controlof both the primary instrument 02 and the secondary instrument 40 whilethe switch is either in the No. 1 or No. 2 position. As many boilers ofthe battery as may be desired can thus be cut off from automaticcontrol, while the remaining boilers of the battery are beingautomatically controlled by the primary controller 2 and the controller40 appurtenant to the particular furnace as heretofore described. Inthis way it is possible to operate a battery of boilers so that theboilers of the battery that are disconnected from the automatic controlcan have their fuel and air manually set to take care of a constantload, or so that the output of these boilers so manually set will beconstant. while the variations in the total load will be taken care ofby the boilers of the battery that are still being controlled by theautomatic controllers 2 and 40. For example, the boiler to which theconnections A (Fig. 2) appertain may be cut off entirely from automaticcontrol by leaving the switch 04 in the No. 1 position (Fig. 3) or inthe No. 2

position (Fig. 4), thus permitting this boiler to care for the steadyload,while other boilers to which connections B and C (Fig. 2) that arelike connections A appertain, may be kept under automatic control byleaving their corresponding switches 04 in the No. 4 position as shownin Fig. 2 to permit these other boilers to care for the variations inloads. In this way any desired number of the boilers of a battery may beisolated from the automatic control and be caused to operate withconstant output, while the remaining boilers are left susceptible to theautomatic control in order to have their output varied with varyingloads.

In the No. 3 position (Fig. 5) of the switch 04, the correspondingboiler is also disconnected from the primary instrument so that itsoutput can be manually set by the push buttons M and L of the secondaryinstrument to care for steady load conditions, while the boilers of thebattery that have their switches 04 in the No. 4 position (Fig. 2) willcare forthe variations in load. At the same time the secondaryinstrument 40 of the boiler or boilers set. for steady ad con itionswill, wit the switch or switches thereoit is in he 110.

position (Fig. the air "for prone tendant at that instrument may bringabout a simultaneous increase o or and air, or a simultaneous decreaseof incl and air, the circuits to the primary instrument for automaticoperation being disconnected.

In this No. 3 position (Fig. the connecti ons from the third tourthsolenoids (wires 513 and the leads through the automatic ci" uitclosers, 60, 61, of the secondary instrument, so the automaticreadjustment control of the air is maintained.

The operation o l apparatus will be readily understood .0111 theforegoing description. lVith the "ches O2 0a in normal position and withthe indicators of the primary and secondary instruments in normalposition, that is, the steam gauge indicating the normal pressure whichit is desired to maintain, and the steam-flow air-flow meter indicatingby coincidence of its pointers that the relation o't steam flow to airflow is such as prevails when the combustion is etlicient, there will beno effective operation of the parts and the condition of the fuel supplyand air supply will remain the same and in proper amount to generate thesteam required at whatever demand then exists or whatever the powerrating at the time maybe.

The feelers of the controlling instruments will, however, continue toperform their periodic to and fro working movements and the shafts ofthe corrector driver will continue to run, although without producingany effect as all of the clutches are disengaged.

If, however, there is a change in demand for power, or call for a changein the rating of the steam plant, the indicator of the primaryinstrument will be moved in one or the other direction according as thesteam pressure falls or rises in response to increased or decreaseddemand. The feelcr of the primary instrument will then operate one orthe other of the circuit closers, 22, 220, according as an increase ordecrease of heat input is called for, thus energizing the first andfifth solenoids ot the corrector driver, or the second and sixth,according as the steam pressure fallen or risen. The energizing of thefirst and fifth solenoids connect the first and fifth clutches and thuscauses the corrcc-tor driver to move, by the first shaft, thecontrolling devic in the direction to give more air supply, and to more,by the litth shaft, the rheostat, 206, in the direction to causeincrease of speed of operation of the fuel feeding motor, 20?.

This operation ot slowly increasing the fuel and air supplies willcontinue for a short interval time, while the feeler is makin its fordunovement towards the indicator and Wlil then cease when the feelerbegins its retru'n movement, so that the correctivc action on th :tueland air supplies is discontinued and new rate of tuel'and air feed isfor the time being established.

it the change in demand for power is comparatively small and themovement of the DTGSU1Q indicator consequently comparalively slow feelerwill produce only a relatively short closure of the circuit and thecorrective action or change of fuel and a feed will be relatively small.It, how ever, the change in demand is'large and the change of pressurerapid, the amount of correction would he correspondingly increase It thechange in pressure did not increase further there would be no furthercorrection at the next operation of the teeler it the change had beensmall, or only a small further correction it the change in pressure hadbeen'somewhat more rapid, but if the change had been sudden and large sothat the yielding stop, 32, for the circuit closer, 22, had been calledinto operation, a further correction of the same character would be madeat the next and at succeeding operations of the feeler until thepressure began to return towards normal.

The retarder, or provision for delaying the return of the automaticcircuit closer of the )rimary instrument to its normal position would,in the case of the small correction first considered, prevent furthercorrective action on the next'and ensuing operations of the teeler andthe appliances would wait for a short period, thus testing, as it were,the effect of the slight correction already made.

It the correction has been sufficient it would, as soon as the increaseof combustion had time to take effect upon the generation of steam,restore the pressure to normal with but slight liability of carrying thechange. beyond normal, so as to require a new correction of the oppositekind.

If, however, the slight correction made were insufiicient the pressurewould continue to change in the same direction as before and would thenbring about an additional corrective action, about the same in amount asthe first, which would be followed by another delay to test the effectof the further correction.

In this way the action of the controller anticipates the effect producedby it and waits until the result of an initial correction is madeevident before making a further corrective action.

However great and rapid the change of pressure may have been, as soon asthe pressure begins to return towards normal the action of the retarderwill be to prevent the feeler from bringing about further correctiveaction, until the pressure is restored to normal.

Thus, except in the case of excessive fluctuations in the demand forpower, the correction is usually effected and the pressure brought backto normal at the new rating without overcorrection and carrying thepressure beyond normal so as to require correction of the opposite kind,or hunting.

Owing to the described eflfective speeds of the first and second shaftsof .the corrector driver, relative to that of the fifth and sixth, whenthe first and fifth shafts are operating to increase the fuel and airsupply the latter will be increased at a relatively higher rate thusproducing an excess of air above what is required for proper combustion,while the change is being made, and similarly when the second and sixthshafts operate to dlmlnish the fuel and air supply the fuel supply is.

' operated more rapidly than the air supply, sci:

that an excess of air is also brought a while making such correction forreducing the input of heat.

The secondary controlling instrument, 40, responds to an excess of airbeyond what is required for efficient combustion for the gen .eration ofthe amount of steam produced, as

indicated by the steam-flow component of the meter, or to a deficiencyof air if such should at any time arise, and by the actlon ofits feelerand circuit closers causes more or less air to be supplied as theindication calls for.

The differential connection between the shaft, 120, for correcting theair supply under control of the primary instrument, and the shaft,operated by the gear 123, for correcting the air under control of thesecondary instrument, permits both corrections to be made concurrentlywhen required, the damper or thing to be corrected responding to thedifferential or algebraic sum of the corrections due to the action ofthe primary and secondary instruments.

The invention is not limited to the mechanical details of the variousinstruments herein shown, as obviously they may be widely varied withoutdeparture from the essential matters oforganization and cooperation ofthe instrumentalities hereinbefore described.

Novel features of the mechanical construction which are not hereinclaimed will form the subject of other applications for patent.

It will be apparent that the organization fs such as to lend itself to agreat Variety of structural organization. Taking into account the factthat the problem of maintaining eificient combustion is exceptionallydiflicult when powdered coal is the fuel used, the construction hereinshown for purposes of illustration is comparatively simple andsufiicient only to show a complete adequate organization of thecooperating elements of the controlling apparatus, which obviously mightbe expanded to include other factors the control of which would benecessary or desirable to complete the effective attainment of theresult desired.

The use of the control apparatus forming a subject of this invention isnot limited to the control of a steam generating plant such as has beentaken to illustrate an embodiment of the invention, as the same orequivalent controlling means might be employed for the regulation of anyvariable, the variations of which may be regulated or controlled bychanging or correcting one or more variable factors, and in which, ifrequired, the variable factors may be correlated to one another as asecondary or readjustment regulation additional to but independent ofthe variation of all of the factors for controlling the variable whichis primarily to be regulated.

I claim 1. An automatic controlling apparatus for maintaining thedesired condition of combustion in a steam generator furnace, comprisingan indicator responsive to changes of steam pressure; correctors forchanging the rate of supply of fuel and air to the furnace, and acontrolling instrument comprising a feeler which has a periodic movementrelative to the indicator and which causes the correctors to operateduring portions of the period of movement of the feeler when theindicator is in abnormal position.

2.. An automatic controlling apparatus for maintaining the desiredcondition of a variable to be regulated, comprising a primary controlinstrument having an indicator responsive to changes of said variable;correctors for changing correlated factors, by which said variable isregulated, and a controlling instrument which causes thepropercorrectors to operate concurrentlywhen the ind cator is in abnormalposition, and a secondary control instrument for varyin one or more ofsaid factor s independent y of the primary control to bring it to properor normal relation to the others.

3. A control system for regulating the operation of a steam generatingplant, comprising a primary instrument having an ind cator movable inresponse to changes of pressure of the steam generated; correctors forchanging the'rate of supply of fuel and of air concurrently to thefurnaces; means responsive to said indicator for causing the saidcorrectors gradually to increase or decrease the rate of supply of thefuel and air controlled by them, and a secondary control instrumenthaving an indicator responsive to change in the relation of steam outputto rate of air supply to the furnace and means responsive to saidindicator for effecting an action of the air flow corrector independentof that responsive to the primary control instrument. I

4. An automatic controlling apparatus for regulating the ratio of fuelto air in a furnace, comprising an indicator responsive to changes ofsaid ratio; correctors for changing one or more factors by which saidratio is regulated; a corrector driver having a continuously running,but normally inactive, means for operating each of said correctors tochange the same gradually in one or the other direction; and acontrolling instrument responsive to the indicator and controlling theeffective engagement of the driver and *correctors.

5. An automatic controlling apparatus for regulating the ratio of fuelto air in a furnace, comprising an indicator responsive to changes ofsaid ratio; correctors for changing one or more factors by which saidratio is regulated and a controlling instrument comprising a feelerwhich has a periodic movement relative to the indicator and hasprovision for causing the correctors to operate during greater or lessportions of the period of movement of the feeler, dependent upon theamount of change of the indicator in one period of said movement.

7 6. An automatic controlling apparatus for maintaining the desiredcondition of a variable to be regulated, comprisingan indicatorresponsive to changes of said variable; correctors for changing one ormore factors by which said variable is regulated and a controllinginstrument comprising afeeler which has a periodic movement relative tothe indicator and has provision for causing the correctors to operateduring greater or less portions of the period of movement of the feeler,dependent upon the amount of changes of the indicator in one period ofsaid movement, and retarding means whereby the effect of the feeler onthe correctors is diminished at its succeeding periods of operation.

7. An automatic controlling apparatus for maintaining the desiredcondition of a variable to be regulated, comprising an indicatorresponsive to changes of said variable; correctors for changing one ormore factors by which said variable is regulated and a controllinginstrument comprising a feeler which has a periodic movement relative tothe indicator and has provision for causing the correctors to operateduring greater or less portions of the period of movement of the feeler,

dependent upon the amount of change of the indicator in one period ofsaid movement. and retarding means whereby the efiect of the feeler onthe correctors is annulled during change of indicator from abnormaltowards normal position.

8. A control system for regulating the operation of a steam generatingplant, comprising an indicator movable in response to changes ofpressure of the steam in the boiler; correctors for changing the rate ofsupply of fuel and air to the boiler furnace, and a controllinginstrument comprising a feeler having a periodic movement relative tothe indicator and cam surfaces for cooperating with the feeler whenmoved in response to departure from normal pressure, and means operatedby said feeler for causing operation of said correctors dependent uponthe direction and extent of change of the indicator in a period ofoperation of the said feeler.

9. A control system for regulating the operation of a steam generatingplant, comprising an indicator movable in response to changes ofpressure in the steam boilers; cor rectors for changing the rate ofsupply-of fuel and air to the boiler furnace; a corrector driver havingcontinuously running means for operating said correctors individuallygradually to increase or decrease the supply of fuel and air controlledby them, said operating means being normally disconnected from the saidcorrector; electromagnetic devices controlling the operative engagementof the driver with the individual correctors for driving the same ineither direction, and a controlling instrument responsive to theindicator, comprising a feeler having a cam surface and a circuit.closer operated thereby controlling the electromagnetic devices of thedriver.

10. A control system for regulating the operation of a steam generatingplant, comprising an indicator movable in response to changes ofpressure of the steam generated; correctors for changing the rate ofsupply of fuel and of air concurrently to the furnaces; a correctordriver having continuously running, but normally inactive, means foroperating said correctors individually gradually toincrease or decreasethe rate of supply of the fuel and air controlled by them; connectingmechanism between said driver and correctors adapted to increase the airsupply at a relatively higher rate than that of the concurrent increasein fuel supply, and to decrease the fuel supply at a relatively higherrate than that of the concurrent decrease in a r supply; a controllinginstrument responslve to the indicator governing the operativeengagement of the driver with the correctors; and a secondary controlinstrument and an independent connect-ion therefrom to the corrector forthe rate of air supply governed thereby to correlate the rate of airsupply to that of fuel supply for efiicient combustion.

11. A control system for regulating the operation of a steam generatingplant, comprising a primary control instrument having an indicatormovable in response to changes of pressure of the steam generated;correctors for changing the rate of supply of fuel and air concurrentlyto the furnaces; a corrector driver having continuously running, but normally inactive, means for operating said correctors concurrentlygradually to increase or decrease the rate of supply of the fuel and aircontrolled by them; means controlled by the indicator for governing theengagement of the driver with the correctors to be operated; asecondarycontrol instrument having an indicator; and means controlled by the saidsecondary indicator for governing the engagement of the driver with thecorrector for the air supply; and a differential connection between thecomponents of the actuating mechanism of the driver for the air supplycorrector which are controlled by the primary and secondaary controlinstruments respectively.

12. A control system for regulating the operation of a steam generatingplant, compris ing a primary control instrument having an indicatormovable in response to changes of pressure of the steam generated;correctors for changing the rate of supply of fuel and of airconcurrently to the furnaces; a corrector driver having a continuouslyrunning but normally inactive means for operating said correctorsconcurrently gradually to increase or decrease the rate of supply of thefuel and air controlled by them; connecting mechanism between saiddriver and the correctors whereby the air supply is increased at arelatively higher rate and is decreased at a rela tively lower rate thanthe concurrent increase or decrease in rate of fuel supply; said primarycontrolling instrument having a feeler provided with a modifying camsurface; means for operating said feeler periodically; and meanscontrolled thereby for efi'ect ing operative engagement of theconnecting mechanism of the driver with the correctors; a secondarycontrol instrument having an indicator responsive to variations inefliciency of combustion and aperiodically operated feeler and meansoperated by said'feeler and indicator which control the operativeengagement of the driver with the air flow corrector,

other than that governed by the primary control instrument.

13. A control system for a plurality of steam boilers feeding a mainline comprising means for initially correcting the supply of fuel andair to said boilers when the pressure in the main line departs from thenormal, and means to prevent further correction of the two until timehas elapsed to test the initial correction.

14. A control system for a plurality of steam boilers feeding a mainline comprising means for initially correcting the supply of fuel andair to said boilers when the pressure in the main line departs from thenormal,

and means to vary the amount of initial cor- V rection in accordancewith the amount of dein the main line departs from the normal, and

means to increase the correction after an in terval of time provided thepressure has in the meantime departed farther from the normal, theincrease in the amount of correction being proportional to the change inboiler pressure during said interval of time.

17. A control system for a plurality of steam boilers feeding a mainline comprising means for changing the supply of fuel and air to saidboilers when the pressure in the main line departs from the normal, andmeans to modify the proportion of fuel and air supplied to each boilerindependently of the proportion of fuel and air supplied to the otherboilers after said change in fuel and air supply has been made.

18. A control system for a plurality of steam boilers feeding a mainline comprising means for initially correcting the supply of fuel andair to said boilers and feeding an excess of air during said correctionwhen the pressure in the main line departs from the normal, and means toprevent further correction of the two until time has elapsed to test theinitial correction.

19. A control system for a plurality of steam boilers feeding a mainline comprising means for changing the supply of fuel and air to saidboilers when the pressure in the main line departs from the normal, andmeans to modify the proportion of fuel and air supplied to each boilerindependently of the proportion of fuel and air supplied to the otherboilers after said change in fuel and air supply has been made until theproportion reaches the maximum efficiency.

20. A control system for a plurality of steam boilers feeding a mainline comprising means for initially correcting the supply of fuel andair to said boilers when the pressure in the main line departs from thenormal, and maintaining a correction at least substantially as great assaid initial correction until the normal pressure is again reached.

21. A control system for a plurality of steam boilers feeding a mainline fc bmprising means for initially correcting the supply of fuel andair to said boilers when the pressure in the main line departs from thenormal, and means to prevent further correction of the two until timehas elapsed to test the initial correction and to produce smallcorrections in the same direction upon further slow departure from thenormal.

22. A control system for use with apparatus having a factor which,during operation of the apparatus, tends to vary from the predeterminedvalue, for maintaining said factor at the predetermined value,comprising means which when operated tends to restore said factor to itspredetermined value and ceases substantially to operate for additionalrestoration of said factor for a period of times sufficiently long totest the effect of its last restorative operation, control meanscomprising mechanism for effecting movement of said means, means wherebythe magnitude of said movements is de pendent upon the rate of departureof said factor from the predetermined value, means whereby upondeparture of the factor an adjustable predetermined amount from thepredetermined value, the successive movements of said first-named meanswill be of a constant magnitude.

23. A control system for use with apparatus having a factor which,during operation of the apparatus, tends to vary from the predeterminedvalue, for maintaining said factor at the predetermined value,comprising means positioned in accordance with variations of said factorfrom the predetermined value, means which when operated tends to restoresaid factor to its predetermined value and ceases substantially tooperate for additional restoration of said factor for a period of timesufficiently long to test the effect of its last restorative operation,and control means through which said first-named means effects operationof said second-named means, said control means comprising mechanism foreffecting movements of said second-named means in each direction, meanswhereby the magnitude of such movements is dependent upon the rate ofdeparture of said factor from the predetermined value, and means wherebyupon departure of the factor an adjustable predetermined amount from thepredetermined value, the successive movements of said first-named meanswill be of a con- 7 stant magnitude.

24. A control system for regulating the operation of a steam generatingplant, comprising a primary control instrument having an indicatormovable in response to changes of pressure of the steam generated,correctors for changing the rate of supply'of fuel and air concurrentlyto the furnaces, a corrector driver having normally inactive motor meansfor operating said correctors concurrently adually to increase ordecrease the rate of supply of the fuel and air controlled by them,

means controlled by the indicator for making the driver effective on thecorrectors to be operated, a secondary control instrument having anindicator, and means controlled by the said secondary indicator formaking the driver effective on the corrector for the air supply, and adifierential connection between the components of the actuatingmechanism of the driver for the air supply corrector which is controlledby the primary and secondary control instruments respectively. V

25. A control system for regulating the operation of a furnace,comprising a primary control instrument having an indicator movable inresponse to a variable factor produced by said furnace, correctors forchanging the rate of supply of fuel and air concurrently to saidfurnace, a corrector driver having normally inactive motor means foroperating said correctors concurrently gradually to increase or decreasethe rate of supply of the fuel and air controlled by them, meanscontrolled by the indicator for making the driver effective on thecorrectors to be operated, a secondary control instrument having anindicator, means controlled by the said secondary indicator for makingthe driver effective on the corrector for the air supply, and adifferential connection between the components of the actuatingmechanism of the driver for the air supply corrector which is controlledby the primary and secondary control instruments respectively.

26. A control system for regulating the operation of'a furnace,comprising a primary control instrument having an indicator movable inresponse to a variable factor produced by said furnace, correctors forchanging the rate of fuel and air concurrently to said furnace, acorrector driver having normally inactive motor means for operating saidcorrectors concurrently gradually to increase or decrease the rate ofsupply of the fuel and air controlled by them, means controlled by theindicator for making the driver effective on the correctors to beoperated, a secondary control instrument having an indicator, meanscontrolled by the said secondary indicator for making the drivereffective on the corrector for the air supply, and a differentialconnection between the components of the actuating mechanism of thedriversfor one of the elements of combustion for the furnace which iscontrolled by the primary and secondary control instrumentsrespectively.

27. An automatic controlling apparatus for maintaining the desiredcondition of a variable to be regulated, comprising an indicatorresponsive to changes of said variable, correctors for changing one ormore factors by which said variable is regulated, a corrector driverhaving normally inactive motor means for operatlng said correctorsconcurrently gradually to increase or decrease the factors controlled bythem, means controlled by the indicator for making the driver effectiveon the correctors to be operated, a secondary control instrument havinganindicator, means controlled by said secondary indicator for making thedriver effective on the corrector of one of the factors, and adifferential connection between the components of the actuatingmechanism of the driver corrector of one of the factors which arecontrolled by the primary and sec- I ondary control instrumentsrespectively.

28. Combustion control apparatus comprising in combination, a furnace,apparatus for supplying the elements of combustion to the furnace, agear driven corrector of the rate of supply for each element, meansresponsive to a factor in furnace operation for concurrently actuatingthe correctors, means responsive to a second factor in furnace operationfor actuating one of the oorrectors, and a diiferential gear connectionbetween said means and said last-named Corrector.

29. A control system for a vapor generator comprising means forinitially correcting the supply of the elements of combustion to thegenerator when the vapor pressure departs from normal, and means toprevent further correction of the elements of combustion until time haselapsed to test the initial correction.

30. A control system for a vapor generator, comprising means forinitially correcting the supply of the elements of combustion to thegenerator when the pressure departs from normal, and means to increasethe correction after an interval of time provided the variable has inthe meantime departed farther from the normal.

31. A control system for maintaining the value of a variable, comprisingmeans for initially correcting a factor influencing the value of saidvariable when the variable departs from the normal, and means toincrease the correction after an interval of time only if the variablehas in the meantime departed farther from the normal.

32. A control system for maintaining the value of a variable, comprisingmeans for initially correcting a factor influencing the value val oftime.

ERVIN G. BAILEY.

